1. Field of the Invention
This invention relates to a control system including a control valve for dual fuel (liquid and gaseous) supply system for an internal combustion engine.
2. Description of the Prior Art
The present invention is concerned with a control system and a control valve for supplying a gaseous supplemental fuel to the intake airstream of an internal combustion engine, in particular a diesel engine, in suitable proportions to provide adequate total heat input to the engine to enable the same to produce the total power output demanded of it while using less of its primary liquid fuel (diesel fuel). The control system for the valve accordingly regulates its operation so that the gaseous fuel is supplied in suitable quantity to achieve the desired porportions of air to supplemental gaseous fuel despite varying engine operating conditions.
The basic control valve used in the invention is described in commonly assigned U.S. patent application Ser. No. 397,168, filed July 12, 1982, now U.S. Pat. No. 4,440,137. Basically, the valve responds directly to intake air flow to proportion supplemental fuel into the airstream under all operating conditions. Prior art examples of this type of valve can be observed in U.S. Pat. Nos. 2,311,315, 3,948,224 and 2,150,764, wherein direct air flow responsive elements are deflected by a moving intake airstream and wherein such movement is used to position a supplemental gaseous fuel valve to regulate admission of the gaseous fuel into the inlet airstream.
The prior art known to applicant is believed not to be concerned, however, with a control valve having a control system capable of adjusting the basic supplemental fuel supply system to accomodate various torque curves of different diesel engines, nor is it known to be concerned with damping sudden motion of the air flow responsive member of the valve. Finally, the prior art is not seen to provide a simple solution for automatically restoring full liquid fuel supply when the gas fuel supply is depleted.